Improvement in the methods of preventing alterations of checks



" UNITED STATES PATENT ()rrron .LOUIS H. G. EHRHARDT, OF PHILADELPHIA,PENNSYLVANIA, ASSIGNOR TO RICHARD B. WIZE, TRUSTEE, OF SAME PLACE.

IMPROVEMENT IN THE METHODS OF PREVENTING ALTERATIONS OF CHECKS, &c.

Specification forming part of Letters Patent No. 150,548, dated May 5,1874 application filed November 3, 1873. e

To all whom it may concern.-

Be itxknown that I, LOUIS HENRY Gus TAVUS EHRHAR'DT, of the city andcounty of Philadelphia and State of Pennsylvania, have invented "a newand useful Process for Preventing Alteration of Checks, Drafts, &c.,reuse of stamps, &c.; and I do hereby declare the following to be aclear and exact description of the nature thereof, sufflcient to enableothers skilled in the art to which my invention appertains to fullyunderstand, make, and use the same.

My invention consists in applying to the surface of checks, drafts,stamps, and other paper, a preparation of such a nature that when fluidof any kind is applied thereto for the purpose of altering; or removingthe writing on the check, &c., or for removing the canceling-ink onstamps, &c., the fluid will combine with the preparation, and cause aninefl'aceable discoloration or stain on the article to which thepreparation has been applied.

In carrying out my invention I take: Sulphate of iron, (dried 210 whitesa1t,) ten parts; gallio acid, ten parts gum sandarac, four parts red oryellow prussiate of potash, one part.

These ingredients are finely pulverized, and well mixed or combined, andconstitute a dry preparation ready for use.

I take a quantity of the preparation and merely rub or otherwisesimilarly apply it in a dry state to the surface of the check, draft,-receipt, document, revenue-stamp, postagestamp, or other article desiredto be protected, either before or-after the same has been written upon,printed, or manufactured,

by the use of any fluid, whether acid, alkaline,

or neutral, such fluid will quickly combine with the ingredients of theapplied preparation, and thus cause a discoloration or stain whereverthe fluid has been applied, thus reliably indicating attempts atalterations of, tampering with, or removal of, the writing or cleansingof stamps previously used and canceled.

All efforts to remove the applied preparation by fluids of any kind willlikewise be indicated by discoloration or stains, and thus the securityof the paper is insured.

Having thus described my invention, what I claim as new, and desire tosecure by Let ters Patent, is

The within-described compound, consisting of the ingredients and inabout the proportions named, or their equivalents, andconstitut-ing adry preparation for application to the surfaces of checks, drafts,stamps, and other papers, and operating to discolor the the paper when afluid is applied thereto, for the purpose set forth.

L. H. e. EHRHARDT.

Witnesses:

J OHN A. WIEDERSHEIM, G. S. HETrtERINeToN.

